Torque limiting clutch

ABSTRACT

Apparatus directed to the art of disengaging an input from an output at predetermined torque values. A torque limiting clutch capable of use as a solid drive unit and a torque limited unit for which the torque disengagement value is selectable. The torque limiting clutch has an overload assembly and a torque drive mechanism which may comprise a plurality of drive pins. Additionally, the torque limiting clutch may comprise seals to discourage contaminants from entering the clutch.

RELATED APPLICATIONS

This application is a division of co-pending U.S. patent applicationSer. No. 14/094,949, filed 3 Dec. 2013, and entitled “Torque LimitingClutch,” which claims the benefit of U.S. Provisional Patent ApplicationSer. No. 61/732,671, filed 3 Dec. 2012, and entitled “Torque LimitingClutch.”

BACKGROUND OF THE INVENTION

The invention relates to releasable torque transmitting couplings and itis concerned more particularly with a self-releasing clutch which willdisengage when a predetermined amount of torque is experienced.

While the principal purpose of torque limiting clutches is to protectvarious types of power driven equipment against overload, such clutcheshave heretofore also been perfected to take care of several specificrequirements. For instance, in many installations it is desirable thatonce the clutch has become disengaged due to an overload it should staydisengaged as long as the overload condition persists, and that theclutch can be reengaged by torque reversal at will when the overloadcondition has abated to the point where operation of the drivenequipment can be resumed. When the clutch idles, that is, while itsdriving member continues to rotate and its driven member is at astandstill, friction losses between the driving and driven members andwear of the relatively engageable and disengageable clutch elementsshould be kept to a minimum.

Further, the torque load at which the clutch becomes disengaged shouldbe precisely fixed, that is, disengagement should take place at theexact moment when the torque reaches a given limit. In its engageddriving condition the clutch should provide a positive drivingconnection between the driving and driven shafts, that is, there shouldbe no gradual yielding between the driving and driven clutch parts. Thedriving connection should be disrupted instantaneously when the giventorque limit has been reached. In some installations it is alsodesirable that the driving and driven clutch parts can be reengaged inonly one rotatively adjusted position relative to each other. Thisrequirement usually has the purpose of maintaining a time relationshipbetween several operating units that are driven from a single powersource. Provisions should also be made to vary the torque limit at whichthe clutch will automatically disengage under an overload, and suchvariation to increase or decrease the torque limit should be possibleconveniently without dismantling the clutch. Another provision which isfrequently desired is that the clutch should be unidirectional, that is,it should provide torque control in one direction and solid drive in theopposite direction. Incorporated herein by reference is U.S. Pat. No.3,893,553.

Additionally, fluid or other contaminates entering a mechanism like thepresent invention may cause premature wear or failure. For example,fluid or other contaminants may enter during a parts cleaning procedure.The where exposure to fluid or dirt is possible, a clutch capable oflimiting the exposure of internal parts to fluids or contaminates wouldbe desirable.

Furthermore, clutch characteristics may change upon clutch break-in.Therefore, a clutch that is manufactured to take into account break-inpatterns would be desirable.

SUMMARY OF THE INVENTION

The invention disclosed herein relates generally to a torque limitingclutch, and more particularly to a more versatile and higher strengthtorque limiting clutch which may comprise additional drive pins to sharetorque loads, sealed components to prevent contaminants from enteringthe clutch, and machined components which replicate break-in wearpatterns to maintain consistent clutch performance characteristics.

One aspect of the invention provides a torque-limited clutch having apositive drive direction and a torque-limited drive direction with anouter clutch assembly and an inner clutch member separated radially by arotor, the outer clutch assembly comprising a first housing coupled to asecond housing, the first housing comprising at least one milled pockethaving a first stop end and a second stop end, the first housing and thesecond housing each comprising a plurality of ball pockets each having aball egress, the rotor comprising a first planar surface and a secondplanar surface wherein a plurality of overload assembly through-holesextend from the first planar surface through the second planar surfaceand at least one drive pin extends outward from the first planarsurface, and a plurality of overload assemblies positioned substantiallywithin the rotor overload assembly through-holes, the plurality ofoverload assemblies each comprising at least one ball and a biasingmechanism, whereby when the torque-limited clutch is used in thepositive drive direction the at least one drive pin is positionedagainst the first stop end of the at least one milled pocket and whenthe torque-limiting clutch is used in the torque-limited drive directionthe at least one ball is biased in one of the plurality of ball pocketsand wherein the at least one ball exits the ball pocket along the ballegress upon the clutch experiencing a torque level exceeding apredetermined torque limit.

The ball egress may be a circumferential chamfer about the ball pocket.

The ball egress may also be a circumferential rounded path about theball pocket.

The ball egress may also be a contoured path following the path of theball during a torque overload.

The milled pocket first stop end and the milled pocket second stop endmay be of substantially similar curvature of the drive pin.

Another aspect of the invention provides a sealed torque-limited clutchhaving a positive drive direction and a torque-limited drive directionwith an outer clutch assembly and an inner clutch member separatedradially by a rotor, the outer clutch assembly comprising a firsthousing coupled to a second housing with a gasket placed therebetween,wherein the first housing is coupled to the second housing withself-sealing type screws, the first housing comprising a first housingprotrusion with a first housing o-ring groove, a first housing o-ringpositioned in the first-housing o-ring groove, and at least one milledpocket having a first stop end and a second stop end the second housingcomprising a second housing protrusion with a second housing o-ringgroove and a second housing o-ring positioned in the second housingo-ring groove, the first housing and the second housing each comprisinga plurality of ball pockets each having a ball egress, the inner clutchhaving an inner clutch first sealing surface and an inner clutch secondsealing surface, wherein the inner clutch first sealing surface is incontact with the first housing o-ring and the inner clutch secondsealing surface is in contact with the second housing o-ring the rotorcomprising a first planar surface and a second planar surface, aplurality of overload assembly through-holes extend from the firstplanar surface through the second planar surface and at least one drivepin extends outward from the first planar surface, and a plurality ofoverload assemblies positioned substantially within the rotor overloadassembly through-holes, the plurality of overload assemblies eachcomprising at least one ball and a biasing mechanism, whereby when thetorque-limited clutch is used in the positive drive direction the atleast one drive pin is positioned against the first stop end of the atleast one milled pocket, and when the torque-limiting clutch is used inthe torque-limited drive direction, the at least one ball is biased inone of the plurality of ball pockets, and wherein the at least one ballexits the ball pocket along the ball egress upon the clutch experiencinga torque level exceeding a predetermined torque limit.

The ball egress may be a circumferential chamfer about the ball pocket.

The ball egress may also be a circumferential rounded path about theball pocket.

The ball egress may also be a contoured path following the path of theball during a torque overload.

The milled pocket first stop end and the milled pocket second stop endmay be of substantially similar curvature of the drive pin.

The first housing ball pockets may each have a first housing threadedchannel extending through the exterior of the first housing whereintorque-adjustment screws may be inserted from the exterior of the firsthousing and through the first housing threaded channel to disengage theat least one ball from the first housing ball pockets.

The torque-adjustment screws may be self-sealing type screws.

The second housing ball pockets may each have a second housing threadedchannel extending through the exterior of the second housing whereintorque-adjustment screws may be inserted from the exterior of the secondhousing and through the second housing threaded channel to disengage theat least one ball from the second housing ball pockets.

The torque-adjustment screws may be self-sealing type screws.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a torque limiting clutch according tothe present invention.

FIG. 2 is a perspective, exploded view of the torque limiting clutch ofFIG. 1 utilizing a proposed embodiment according to the presentinvention.

FIG. 3 is a perspective view of an embodiment of the inner hub shown inFIG. 2.

FIG. 4 is a perspective view of an embodiment of the rotor shown in FIG.2.

FIG. 5 is a side view of the torque limiting clutch shown in FIG. 1.

FIG. 6 is a cross-sectional view of the torque limiting clutch alongline 6-6 of FIG. 1.

FIG. 7A is a cross-sectional view of the torque limiting clutch alongline 7A-7A of FIG. 1 in a drive position.

FIG. 7B is a cross-sectional view of the torque limiting clutch alongline 7B-7B of FIG. 7A engaged in a solid drive rotation.

FIG. 7C is a cross-sectional view of the torque limiting clutch alongline 7C-7C of FIG. 7A engaged in a solid drive rotation.

FIG. 8A is a cross-sectional view of the torque limiting clutch alongline 8A-8A of FIG. 1 in a disengaged position.

FIG. 8B is a cross-sectional view of the torque limiting clutch alongline 8B-8B of FIG. 8A in a disengaged position.

FIG. 8C is a cross-sectional view of the torque limiting clutch alongline 8C-8C of FIG. 8A in a disengaged position.

FIG. 9A is a cross-sectional view of the torque limiting clutch alongline 9A-9A of FIG. 8A during the process of clutch re-engagement.

FIG. 9B is a cross-sectional view of the torque limiting clutch alongline 9B-9B of FIG. 8A during the process of clutch re-engagement.

FIG. 9C is a cross-sectional view of the torque limiting clutch alongline 9C-9C of FIG. 7A re-engaged.

FIG. 9D is a cross-sectional view of the torque limiting clutch alongline 9D-9D of FIG. 7A re-engaged.

FIG. 10A is an exploded view of a second embodiment of the torquelimiting clutch according to the present invention with a switch plate.

FIG. 10B is an exploded view of the torque limiting clutch of FIG. 10Awithout the switch plate.

FIGS. 11A and 11B illustrate the first housing with a second embodimentmilled pocket according to the present invention.

FIGS. 12A and 12B illustrate the first housing with a second embodimentball pocket according to the present invention.

FIGS. 13A and 13B illustrate the second housing with a third embodimentball pocket according to the present invention.

FIGS. 14A and 14B illustrate the first housing with the third embodimentball pocket shown in FIGS. 13A and 13B without threaded channelaccording to the present invention.

FIGS. 15A and 15B illustrate the first housing with a fourth embodimentball pocket according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Although the disclosure hereof is detailed and exact to enable thoseskilled in the art to practice the invention, the physical embodimentsherein disclosed merely exemplify the invention which may be embodied inother specific structures. While the preferred embodiment has beendescribed, the details may be changed without departing from theinvention, which is defined by the claims.

As shown in FIG. 1, an assembled view of an embodiment of the torquelimiting clutch 10 according to the present invention is depicted. Afirst housing 110 and a second housing 150 are married together tocreate an outer clutch assembly 100 in which a rotor 400 (see FIG. 2)and an inner hub body 350 (see FIG. 2) reside. Each housing 110 and 150has through-holes 114 and 154 (see FIG. 2) that align with threadedholes 156 and 116 (see FIG. 2), respectively, of the other housing toallow for a secured assembly with assembly screws 170 (see FIG. 10A).

Continuing with FIG. 2, an exploded view of the torque limiting clutch10 embodying the invention is shown. It comprises the outer clutchassembly 100 comprising the first housing 110 and the second housing150; a drive key 200; the inner hub 300; at least one overload assembly500 comprising torque adjustment screws 510, balls 520, and coil springs540; and the rotor 400 which radially surrounds the inner hub 300 and isitself enclosed within the outer clutch assembly 100.

The first housing 110 comprises a substantially hollow cylindrical shapecomprising a first planar surface 118 recessed within the first housing110 and perpendicular to the central axis, a second planar surface 120defining an interface, and an exterior planar surface 124 opposite thesecond planar surface 120. Extending along the first housing 110 betweenthe first planar surface 118 and the second planar surface 120 is aninner surface 122 and extending along the first housing 110 between thefirst planar surface 118 and the exterior planar surface 124 is abearing surface 126 (best seen in FIG. 11A) in which a sleeve bearing102 is placed.

Additionally, an arcuate seating recess 112 is shown positioned in theinner surface 122 and at least one drive pin pocket 494 is located inthe first planar surface 118.

Furthermore, the first planar surface 118 of the first housing 110 hasball pockets 530 in which the balls 520 of the overload assemblies 500sit when the torque limited clutch 10 is in the drive position,discussed infra. For a more detailed look at the ball pockets 530 of thefirst housing 110 see FIG. 11B. The ball pockets 530 are shown having anon-tapered sidewall 528 with a diameter D that is slightly less thanthe diameter of the balls 520, thereby permitting each engaged ball 520to sit in the respective ball pocket 530 wherein a minority of the ball520 resides in the ball pocket 530, thus promoting departure of the ball520 from the ball pocket 530 upon a torque overload, discussed furtherbelow.

A second embodiment ball pocket 550 is shown in FIGS. 12A and 12B,wherein a chamfered path 552 extends about the periphery of the ballpocket 550.

Additionally, a third embodiment ball pocket 532 is depicted in FIGS.13A and 13B. Here, the ball pocket 532 has a contoured path 534. Thecontoured path 534 provides a smoother egress for the residing ball 520and reduces the break-in time as the path of egress is pre-formed, notformed over time by continuous wear. It is contemplated further that asecond contoured path (not shown) may be formed opposite the firstcontoured path 534.

A method for producing the contoured path 534 may comprise providingtooling (not shown) for drilling the ball pocket 532, drilling the ballpocket 532, forming the contoured path 534 with the tooling as thetooling exits the ball pocket 532.

Moreover, a fourth embodiment 536 of the ball pockets is shown in FIGS.15A and 15B. Here the ball pocket 536 has a circumferential rounded path538 for much the same reason as the contoured at 534 shown in FIGS. 13Aand 13B.

Generally the radius of the contoured path 534 and the rounded path 538will allow the ball to have a rolling contact with the rounded path 538rather than a point contact as may occur with a non-contoured path likethat of the ball socket 530.

Sleeve bearings 102 may be placed in contact with the bearing surface126. A sleeve bearing 102 promotes smooth rotation of the inner hub 300relative to the outer clutch assembly 100. Although roller-type bearingsare depicted here, other types of bearings or bushings are alsocontemplated by the present invention.

The second housing 150 is nearly a mirror image of the first housing 110whereby it has a first planar surface 158 having ball pockets 530, asecond planar surface 160, an exterior planar surface 164, an innersurface 162 having an arcuate seating recess 152, and a bearing surface166 for placement of a sleeve bearing 102.

Looking now to the inner hub 300 but still referring to FIG. 2 andadditionally to FIG. 3, the inner huh 300 has an exterior surface 310,which has a slightly smaller diameter than the inner diameter of therotor 400. This slight variance allows for rotational movement of theinner hub 300 relative to the rotor 400, while minimizing movement in aradial direction. Additionally, the inner hub 300 has two ends 340 whichare positioned within the hearings 102 of the first housing 110 and thesecond housing 150. Furthermore, a tangential pocket 610 is located onthe exterior surface 310. The pocket 610 interfaces with a detentassembly 600 comprising a plunger 630 and a coil spring 640.Additionally, there is an arcuate seating recess 320 located in theexterior surface 310

FIG. 4 illustrates the rotor 400. The rotor 400 has a series of coilspring through-holes 470 that extend through the first planar surface410 and the second planar surface 420 (hidden). Additionally, there isat least one drive pin opening 450 on the first planar surface 410.Furthermore, the rotor 400 has a key slot 460 extending from the secondplanar surface 420 towards, but not to, the first planar surface 410,and extends through the outer surface 440 and the inner surface 430. Thesize of the key slot 460 corresponds to the diameter of the drive key200 (see FIG. 2).

The rotor 400 also has a plunger through-hole 480 extending through theouter surface 440 and the inner surface 430. It is in the plungerthrough hole 480 in which the plunger 630 of the detent assembly 600resides. The plunger through-hole 480 is positioned so as not tointerfere with any of the coil spring through-holes 470 and so that atleast a portion of the plunger through-hole 480 is at a position alongthe rotor's outer surface 440 so that the plunger 630 will not plungeinto the arcuate seating recess 320 of the inner hub 300 when there isan overload and the inner hub 300 rotates freely relative to the rotor400.

The drive key 200 resides in inner clutch arcuate seating recess 320 andthe rotor key slot 460 when the clutch 10 is in the drive position.However, the drive key 200 resides in the rotor key slot 460 and thefirst and second housing arcuate seating recesses 112 and 152 when theclutch 10 is in a disengaged state, discussed further below.

Additionally, the torque limiting clutch 10 has a torque drive means 490comprising at least one drive pin 492 having a first end 494 and asecond end 496. The drive pin first end 494 is pressed into the drivepin opening 450 in the first planar surface 410 of the rotor, and thedrive pin second end 496 resides in a milled pocket 498 located in thefirst planar surface 118 of the first housing 110 (as shown in FIG. 6).The milled pocket 498 in the embodiment shown is larger than the drivein 492. This allows the drive pin 492, and the rotor 400 it is pressedinto, to rotate to some degree in order to allow the overload assemblies500 to disengage (shown in FIG. 8C).

Alternatively, FIG. 11A illustrates an alternative milled pocket 894.The milled pocket 894 comprises a slot extending from a first stop end896 to a second stop end 898. The first stop end 896 and the second stopend 898 are arcuate to substantially match the curvature of the drivepin 492. Additionally, the milled pocket 894 is milled into the firsthousing first planar surface 118 to follow the same path as the drivepin 492. As the milled pocket 894 is more adaptive to the shape andtravel path of the drive pin 492, less material is removed from thefirst housing 110 which provides more rigidity (especially if more thanone drive in 492 are utilized) and promotes a more consistent and solidbushing/bearing 102 fit.

Continuing to look at FIG. 4, along with FIGS. 11A and 5, a plurality ofdrive pins 492 and a plurality of milled pockets 894 are shown.Additional drive pins 492 located in additional milled pockets 894 willdisperse the load more evenly across the outer clutch assembly 100 andwill also increase the amount of force that may be transferred from aninput shaft 20 to an output shaft 30 when the clutch is being used in anon-torque limiting direction (discussed further below) because theforce will be more evenly divided among the drive pins 492. It should beunderstood that reference to the input shaft and the output shaft is forreference only and therefore should not limit the torque limiting clutchto only this operational orientation.

FIG. 7A is a cross-sectional view of the torque limiting clutch 10,further illustrating the internal elements. Here, it can be seen thateach overload assembly 500 comprises torque adjustment screws 510, balls520 residing in their respective ball pockets 530 located in the firstand second housings 110 and 150, and coil springs 540 located in theirrespective coil spring through-holes 470. Additionally, nitrogencylinders or Belleville springs or another type of biasing mechanismknown to one having ordinary skill in the art may be used in place of,or in conjunction with, the coil springs 540.

Furthermore, the torque required to disengage the torque limiting clutch10 is determined by how many of the overload assemblies 500 are active.The overload torque setting may be adjusted by adding or removing shortor long torque adjustment screws 510. For example, if less overloadtorque is desired, long torque adjustment screws 510 are installed. Theadditional length of the long screw pushes the ball 520 out of itspocket 530 and into the through-bore 470, thereby removing it fromcontact with the respective housing 110 or 150. Installing long torqueadjustment screws 510 in each end of an overload assembly 500effectively disengages that overload assembly 500 making disengagementof the torque limiting clutch 10 achievable under less overload torque.Conversely, if more overload torque is desired, more of the overloadassemblies 500 should be activated. This is accomplished by replacinglong screws with short screws until the desired overload torque isachieved.

Additionally, a sealed torque limiting clutch 700 more impervious tofluid or other contaminants is also contemplated by the presentinvention and is depicted in FIGS. 10A and 10B. FIG. 10A depicts asealed torque limiting clutch 700 with switch plate 40. The sealedtorque limiting clutch 700 comprises a first sealed housing 710 and asecond sealed housing 750, an extended inner clutch member 770, and agasket. As the sealing elements of the first sealed housing 710 arehidden from view in this figure, explanatory focus will be placed on thesimilar sealing elements of the second sealed housing 750. As shown, thesecond sealed housing 750 comprises an o-ring protrusion 752 and ano-ring groove 754. Similarly, the first sealed housing 710 comprises ano-ring protrusion 712 and an o-ring groove 714, both hidden here butvisible in FIG. 14A.

Furthermore, the extended inner clutch member 770 comprises a firstsealing surface 772 and a second sealing surface 774.

Additionally, the gasket 780 provides a sealed junction between thefirst sealed housing 710 and the second sealed housing 750. Moreover,housing o-rings 790 placed in the o-ring grooves 714 and 754 maycomprise dynamic o-rings (for example, those made by Parker-HannifinCorp.) as they will be used in a location subject to rotary movement ofthe extended inner clutch member first sealing surface 772 and theextended inner clutch member second sealing surface 774 when the clutch700 is in a disengaged state.

Furthermore, the switch plate 40 comprises studs 42 having rounded tips44 that are inserted through switch plate holes 716 in at least one ofthe first sealed housing 710 and the second sealed housing 750 and whichreside in depressions 482 in the rotor 400. When the clutch 700experiences a disengaging torque, the rotor 400 rotates while the switchplate studs 42 remain relatively stationary causing them to be forcedout of the depressions 482 and against the planar surface 410, 420 ofthe rotor 400. The lateral movement of the studs 42 relative to theclutch 700 is transferred to the switch plate 40 and moves the switchplate 40 to make a signaling connection, whether electrical ormechanical, to signal the torque overload. O-rings 46 located on thestuds 42 reduce the likelihood of fluid or other contaminates enteringthe clutch 700 through the switch plate holes 716.

FIG. 10B shows the sealed torque limiting clutch 700 of FIG. 10A butwithout the switch plate 40. As the switch plate 40 is absent, theswitch plate holes 716 may be filled with plugs 50 incorporating o-rings46 to decrease the potential of fluid or other contaminates fromentering the clutch 700.

Moreover, as shown in FIGS. 14B and 15B, ball pockets 532 and 536 do nothave a threaded channel 526 like those illustrated in FIGS. 11B, 12B,and 13B. This design feature may be provided to further reduce thelikelihood of fluid or other contaminates from entering the clutch 700.However, it is also contemplated that this design feature may bepreferable on only one of the housings 710, 750 because adjustability ofthe amount of force required to disengage the clutch 700 may still bedesired.

Furthermore, it is contemplated that certain pieces of the clutch 700may comprise stainless steel and the screws (i.e., the assembly screws170 and the torque adjustment screws 510) in the clutch 700 may compriseself-sealing stainless steel screws to further limit damage due toexposure to fluid or other contaminants. As a non-limiting example,ZAGO® seal screws may be used.

It is contemplated that the sealing measures herein disclosed reduce thelikelihood of contaminants from entering the clutch 700 under pressure.The sealing measures would preferably maintain a seal up toapproximately 14 psi, but maintaining a seal at greater pressures isalso contemplated.

Additionally, it should be known that the switch plate 40 may be usedwith the non-sealed torque limiting clutch 10 as well; however, theo-rings 46 may be optional.

Drive Position

FIG. 7A illustrates the clutch 10 according to the present invention inthe drive position. In the drive position, the clutch 10 may be used inthe torque limiting direction, as described below, or in a non-torquelimiting direction as a solid drive unit (as depicted in FIGS. 7B and7C). In FIG. 7A, the overload assemblies 500 are engaged with the balls520 located in their respective ball pockets 530. FIG. 7B shows detentassembly 600, wherein the plunger 630 is abutting a wall 620 of thetangential pocket 610. Furthermore, the drive key 200 is locatedpartially in the arcuate seating recess 320 of the inner hub 300 and thekey slot 460 of the rotor 400, thereby operably joining the rotor 400and the inner hub 300 together. FIG. 7C illustrates the at least onedrive pin 492 abutting the wall of the milled pocket 494 at point A,thereby operably joining the outer clutch assembly 100 to the rotor 400.When used as a solid drive unit, the clutch 10 transfers input forcefrom the input shaft 20 to the output shaft 30 through the at least onedrive pin 492 in the direction of the arrows. All in all, the outerclutch assembly 100, the rotor 400, and the inner hub 300 are alloperably joined together and move as one when in the drive position.

Torque Overload State

FIGS. 8A-C show the torque limiting clutch 10 when disengaged due to atorque overload. When the clutch 10 is used in the torque-limitingdirection (the reverse of the solid drive direction), the input force istransferred from the input shaft 20 to the output shaft 30 through theoverload assemblies 500. Therefore, when a force is experienced by theclutch 10 that exceeds the predetermined torque limit, the clutch 10will disengage.

On a global level, in the event of a torque overload the inner hub 300disengages from operable engagement with the rotor 400, therebydisengaging the outer clutch assembly 100 and allowing the inner hub 300to rotate independently. On a more local level, when the clutch 10 is inthe drive position as depicted in FIGS. 7A-C, the inner hub 300 and therotor 400 are separably fixed together by the drive key 200. When a loadabove the torque limit of the overload assemblies 500 is experienced,the excessive load causes the balls 520 of the overload assemblies 500to overcome the spring force of the coil springs 540 and roll out oftheir respective ball pockets 530. The inner hub 300 and the rotor 400then continue to rotate, but independent of the outer clutch assembly100.

Looking at FIGS. 8B and 8C, as the inner hub 300 and the rotor 100rotate together, the rotor 400 is stopped when the at least one drivepin 492 makes contact with the wall of the milled pocket 494 at point B.At this position the arcuate seating recesses 112 and 152 (not shown) ofthe outer clutch assembly 100 are in line with the drive key 200 and thearcuate seating recess 320 of the inner hub 300. As the rotor 400 is nowprohibited from further rotation, the continuing input force willfurther rotate the inner hub 300 relative to both the rotor 400 and theouter clutch assembly 100. As the inner hub continues to rotate, thearcuate seating recess 320 of the inner hub 300 acts against the drivekey 200 and forces the drive key 200 into the arcuate seating recesses112 and 152 (see FIG. 13A) of the outer clutch assembly 100, therebyoperably linking the rotor 400 and the outer clutch assembly 100 andallowing the inner clutch member 300 to rotate independently of therotor 400 and the outer clutch assembly 100. Adjustment to the amount ofoverload force needed to disengage the clutch is achieved through thenumber of active torque adjustment screws 510 (shown in FIG. 7A) asdiscussed supra.

Re-Engagement of the Clutch

After an overload disengages the clutch 10, and the cause for theoverload has been remedied, the clutch 10 may be reset to the driveposition. This is accomplished by either rotating the inner hub 300, theouter clutch assembly 100, or both, in a direction opposite one another.As illustrated in FIG. 9A, the inner hub 300 is rotated in the soliddrive direction. Looking to FIG. 9B, as the inner hub 300 is rotated,the plunger 630, which is biased against the inner hub 300 by the spring640 acting against the inner surface 122 of the outer clutch assembly100, abuts the wall 620 of the tangential pocket 610 located within theexterior surface 310 of the inner hub 300. This operably links the innerhub 300 and the rotor 400. The two continue to rotate together in thesolid drive direction and the key slot 460 acts against the drive key200, and the drive key 200 moves from the arcuate seating recesses 112and 152 (see FIG. 13A) of the outer clutch assembly 100 to the arcuateseating recess 320 of the inner huh 300.

Further rotation permits the balls 520 of the overload assemblies 500 toreseat in their respective ball pockets 530 (see FIG. 9C). Moreover, theat least one drive pin 492 is one again engaged with the wall of itsrespective milled pocket 494 at point A (as shown in FIG. 9D) andthereby re-engaging the clutch 10 in the drive position.

The foregoing is considered as illustrative only of the principles ofthe invention. Furthermore, since numerous modifications and changeswill readily occur to those skilled in the art, it is not desired tolimit the invention to the exact construction and operation shown anddescribed. While the preferred embodiment has been described, thedetails may be changed without departing from the invention, which isdefined by the claims.

We claim:
 1. A torque-limited clutch having a positive drive directionand a torque-limited drive direction comprising: an outer clutchassembly and an inner clutch member separated radially by a rotor; theouter clutch assembly comprising a first housing coupled to a secondhousing; the first housing comprising at least one milled pocket havinga first stop end and a second stop end; the first housing and the secondhousing each comprising a plurality of ball pockets each having a ballegress; the rotor comprising a first planar surface and a second planarsurface wherein a plurality of overload assembly through-holes extendfrom the first planar surface through the second planar surface and atleast one drive pin extends outward from the first planar surface; and aplurality of overload assemblies positioned substantially within therotor overload assembly through-holes, the plurality of overloadassemblies each comprising at least one ball and a biasing mechanism;whereby, when the torque-limited clutch is used in the positive drivedirection the at least one drive pin is positioned against the firststop end of the at least one milled pocket; and when the torque-limitingclutch is used in the torque-limited drive direction the at least oneball is biased in one of the plurality of ball pockets and wherein theat least one ball exits the ball pocket along the ball egress upon theclutch experiencing a torque level exceeding a predetermined torquelimit.
 2. The torque-limited clutch of claim 1, wherein the ball egressis a circumferential chamfer about the ball pocket.
 3. Thetorque-limited clutch of claim 1, wherein the ball egress is acircumferential rounded path about the ball pocket.
 4. Thetorque-limited clutch of claim 1, wherein the ball egress is a contouredpath following the path of the ball during a torque overload.
 5. Thetorque-limited clutch of claim 1, wherein the milled pocket first stopend and the milled pocket second stop end are of substantially similarcurvature of the drive pin.